NEMA RN 2-1997（R2001、R2009、R2018）涵盖了长度为10英尺（3.05米）的电气刚性金属导管（ERMC）-钢、电气中间金属导管（EIMC）-钢和电气金属管（EMT）-钢主束的尺寸和绑扎建议，以及长度为20英尺（6.10米）的ERMC钢和EMT钢主束的尺寸和绑扎建议。

NEMA RN 2-1997 (R2001, R2009, R2018) covers recommendations for the size and banding of master bundles of electrical rigid metal conduit (ERMC)-steel, electrical intermediate metal conduit (EIMC)-steel, and electrical metallic tubing (EMT)-steel, in 10-foot (3.05 m) lengths and the size and banding of master bundles of ERMC-steel and EMT-steel, in 20-foot (6.10 m) lengths.